Method for driving a vehicle with manually shifted transmission, automatic transmission or continuous transmission on streets with low friction value

Abstract

A method for operating a motor vehicle with a manual transmission, a multi-ratio automatic transmission or a continuously variable transmission, on a road with a low friction coefficient, the engine torque is reduced or, as the case may be, decreased, which leads to a reduction of the wheel drive torque without changing the starting gear ratio.

1. A method for operating a motor vehicle with one of a manual transmission, multi-ratio automatic transmission or a continuously variable transmission on a road having a low friction coefficient, the method comprising the steps of:
 providing a standard driving program in a transmission control for controlling one of the manual transmission, multi-ratio automatic transmission or the continuously variable transmission according to a plurality of desired transmission gear ratios, including a transmission starting gear ratio; 
 switching from the standard driving program in the transmission control to a modified driving program for the mad having a low friction coefficient; 
 reducing an engine torque in the modified driving program to accordingly reduce a wheel drive torque without changing the engine speed; and 
 maintaining the transmission starting gear ratio of the standard driving program in the modified driving program. 
 
   
   
     2. The method according to  claim 1 , further comprising the step of directly reducing tie engine torque according to one of an engine controller and by transmission engagement with an engine. 
   
   
     3. The method according to  claim 1 , further comprising the step of determining a value of the engine torque as a function of the engine speed and a gas pedal value and modifying the value of the engine torque in such a way so as to be reduced in comparison with the standard program. 
   
   
     4. The method according to  claim 1 , wherein engine torque in the modified driving program as compared to the standard driving program, is modified by a factor k dependent on at least one of an engine speed, a gear ratio, a vehicle speed and a gas pedal value. 
   
   
     5. The method according to  claim 1 , further comprising the step of corresponding engine torque values at a high gas pedal value in the modified driving program to value of the standard driving program. 
   
   
     6. The method according to  claim 1 , further comprising the step of relating desired reduction levels of engine torque to relative road friction coefficients and modifying the engine torque accordingly. 
   
   
     7. A method for operating a motor vehicle with a continuously variable transmission on a road having a low friction coefficient, the method comprising the steps of:
 providing a standard driving program in a transmission control for controlling the continuously variable transmission according to a plurality of desired transmission gear ratios, Including a transmission starting gear ratio; 
 switching from the standard driving program in the transmission control to a modified driving program for the road having a low friction coefficient; 
 reducing an engine torque in the modified driving program to accordingly reduce a wheel drive torque without changing the engine speed; and 
 maintaining the transmission starting gear ratio of the standard driving program in the modified driving program. 
 
   
   
     8. The method for operating a motor vehicle with a continuously variable transmission on a road having a low friction coefficient as set forth in  claim 7 , the method further comprising the steps of reducing the engine torque in the modified driving program to accordingly reduce the wheel drive torque without changing the engine speed in either forward and reverse driving gears of the motor vehicle. 
   
   
     9. A method for operating a motor vehicle with one of a manual transmission, mult-ratio automatic transmission or a continuously variable transmission on a road having a low friction coefficient, the method comprising the steps of:
 providing a standard driving program defining an engine torque value as a function of at least a gas pedal value and an engine speed in a transmission control for controlling one of the manual transmission, multi-ratio automatic transmission or the continuously variable transmission according to a plurality of desired transmission gear ratios, including a transmission starting gear ratio; 
 modifying the engine torque value to obtain a modified driving program having a reduced engine torque value and a reduced wheel torque value in comparison to the standard driving program; 
 switching from the standard driving program in the transmission control to the modified driving program for the road having a low friction coefficient; and 
 maintaining the transmission starting gear ratio of the standard driving program in the modified driving program. 
 
   
   
     10. The method for operating a motor vehicle with a continuously variable transmission on a road having a low friction coefficient as set forth in  claim 9 , the method further comprising the steps of modifying the engine torque value to obtain the modified driving program having the reduced engine torque value and the reduced wheel torque value in comparison to the standard driving program while maintaining the engine speed and gas pedal value. 
   
   
     11. The method for operating a motor vehicle with a continuously variable transmission on a road having a low friction coefficient as set forth in  claim 10 , the method further comprising the steps of determining a desired range for the gas pedal value within which the engine torque will not be reduced. 
   
   
     12. The method for operating a motor vehicle with a continuously variable transmission on a road having a low friction coefficient as set forth in  claim 11 , the method further comprising the steps of reducing the engine torque in the modified driving program to accordingly reduce the wheel drive torque without changing the engine speed in either forward and reverse driving gears of the motor vehicle.